Plot the energy of a typical professional talk across time and you get a recognisable shape: a confident first ninety seconds, a long sag, and a slightly relieved finish. We see it constantly, and it has a simple cause.
You rehearsed the opening. You improvised the rest.
What an energy arc actually is
Energy in speech is not volume. It is a composite: how loud you are, how much your pace varies, and how far your pitch moves. Monotone is low energy even when it is loud. A quiet, varied delivery can be high energy.
Measured in ten-second windows and smoothed, the resulting curve has a shape, and the shape has a name. Building. Front-loaded. Peaked early. Inverted-U. Strong open that fades. Flat. Variable.
The shapes and what they signal
Strong open, fades. The most common. You are prepared for the start and running on memory afterwards. The room concludes your best material came first, whether or not it did.
Peaked early. A high point in the first third, then a long descent. Usually means the argument was resolved too soon and what followed was supporting detail nobody asked for.
Inverted-U. Builds, peaks in the middle, declines. Strong structurally, weak at the close — the ending is where it leaks.
Flat. Even throughout. Feels safe from the inside; from the outside it removes the listener's cues about what mattered.
Building to close. The rarest and the most effective. Energy rises through the talk and peaks in the final third, so the room leaves at your high point.
Why the middle sags
Three reasons, in order of frequency. The middle was never rehearsed, only outlined. The middle carries the detail, and detail invites a flatter register. And by minute three, adrenaline from the opening has metabolised, taking your projection with it.
None of these are personality. All three are preparation.
Fixing it
Rehearse the middle, not the opening. Everyone over-prepares the first ninety seconds because that is where the fear is. The return on effort is inverted.
Then plant deliberate lifts. Pick two moments in the middle third — a number, a story, a direct question to the room — and treat each as a small opening in its own right. Energy does not have to be sustained. It has to be reintroduced.
And end on the high. Whatever your strongest line is, it does not belong in minute two.
Start your first session — record three minutes and see how you actually land. It is free and takes about three minutes.
Related reading
What is executive presence — and why most communication advice gets it wrong · 14 dimensions of communication that determine whether you move a room · The gap between how you think you sound and how you actually land
Preparing something specific? Investor pitch · Sales calls · Presentations · Difficult conversations · Interview practice